This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The plant defense response to pathogens relies primarily on the use of pre-existing physical barriers and inducible defenses, which require massive transcription of defense genes. Among the genes induced during the response defense, PR-10a is the best characterized. It is activated by a transcription activator termed StWhy1 (Solanum tuberosum Whirly 1) which recognize single-strand DNA. StWhy1 is ubiquitous among plants kingdom but is not related to any other protein in other kingdoms. The crystal structure of the uncomplexed form of StWhy1 was solved by us. Structural analyses of StWhy1 have suggested that the protein binds DNA in a novel way but the binding mechanism has not been characterized yet. We therefore propose to solve the structure of a StWhy1/DNA complex to characterize the binding of the protein to its cognate DNA element. Crystals of the protein/DNA complex have already been obtained. They diffract to 7A in our own X-rays generator. The use of high-flux beamline would enable us to obtain high diffraction pattern and permit us to solve the protein-DNA complex structure. This would give us insight into the mechanism of DNA binding by StWhy1 as well as its activation of transcription.